AP PHOTO In this Aug. 12 photo, Iowa Gov. Kim Reynolds attends the opening day of the Iowa State Fair in Des Moines. Public health officials in Iowa’s largest county are sounding alarms that too few people are wearing masks and getting vaccinated as coronavirus cases and hospitalizations climb.

DES MOINES — Public health officials in Iowa’s largest county are sounding alarms that too few people are wearing masks and getting vaccinated as coronavirus cases and hospitalizations climb in the state to levels not seen since January.

The surge of the COVID-19 delta variant comes as children return to schools that are barred from requiring face coverings due to a law approved earlier this year by the Republican-controlled Legislature and signed into law by GOP Gov. Kim Reynolds.

In its weekly update Wednesday, the Iowa Department of Public Health noted 42 deaths due to the coronavirus since last week’s report, bringing the state total to 6,268 deaths.

The state reported 7,619 positive tests in the past seven days. In six of the past 10 days, Iowa posted more than 1,000 positive tests a day.

The report shows that more young people are becoming infected. In the past seven days, 17% of the state’s positive tests were among those under age 17, up from 13%.

Officials are especially concerned in Polk County, which just hosted more than 1 million visitors to the Iowa State Fair, where mask wearing was voluntary and large crowds gathered for concerts and indoor events. The county has 82,000 children under age 12 who do not qualify for vaccination and are vulnerable to infection, said Polk County Health Department Director Helen Eddy.

“Our hospitals are full. Our healthcare workers are tired. Parents and guardians are scared to send their children to schools,” Eddy said Tuesday in a statement as she pleaded for people to get vaccinated and wear masks again in public.

Public health officials said it will be difficult to track cases back to the 11-day fair in Des Moines. It’s likely to take at least five days for symptoms to show up and seven to 10 days for cases to be seen in the data, said Dr. Meghan Schaeffer, an epidemiologist working as a consultant for Polk County.

In Polk County, 54.7% of population is fully vaccinated and coronavirus cases have increased 175% in the past three weeks. Area hospitals have 109 COVID-19 patients.

“We have not seen a trend in COVID-19 hospitalizations like this since the last COVID-19 surge, which took place in October of 2020,” the Polk County Health Department said in Tuesday’s statement. Four of the hospitalized are under age 18, the highest number of patients that young the county has seen.

County health officials said they expect the surge in new cases to continue because school has started and people “are not following COVID-19 prevention strategies, including wearing masks in public indoor settings.”

According to data from the U.S. Centers for Disease Control and Prevention, 91 of Iowa’s 99 counties have a high rate of spread. The remaining eight are in the substantial spread category.

In western Iowa, the AHSTW school district postponed the first day of classes from Tuesday to Aug. 30 after several staff members tested positive for COVID-19 and many more were exposed. It’s the first example of the aggressively spreading delta variant complicating the start of school this year in Iowa.

The staff members of the Des Moines Public Schools administrative building were working remotely due to an outbreak just days before school started. The building was to remain closed through Friday. School started in the state’s largest district on Wednesday with 33,000 students and nearly 5,000 employees.